Manual Transmission - CDV Question

[RElias21]

Hey Folks,

I have a 6MT ZCP F80 with a Stage 1 93Oct BM3 tune, and as I've recently started to drive the car harder, I've noticed a little delay in power coming on immediately after a quick shift.

If my memory serves me correctly, my old 2010 335 used to have a similar issue caused by a Clutch Delay Valve. I think it was a pretty simple swap in that car.

Does anyone know if there is a CDV in the F80, and if that is the cause of what I'm feeling? I have not been able to find a definitive answer from searching. Alternatively, anyone have any suggestion re: how to remedy this issue?

Thanks!

[Djdnav]

Originally Posted by RElias21

Hey Folks,

I have a 6MT ZCP F80 with a Stage 1 93Oct BM3 tune, and as I've recently started to drive the car harder, I've noticed a little delay in power coming on immediately after a quick shift.

If my memory serves me correctly, my old 2010 335 used to have a similar issue caused by a Clutch Delay Valve. I think it was a pretty simple swap in that car.

Does anyone know if there is a CDV in the F80, and if that is the cause of what I'm feeling? I have not been able to find a definitive answer from searching. Alternatively, anyone have any suggestion re: how to remedy this issue?

Thanks!

I don't know if it's the cause of your issue, but there is a CDV. It's pre-installed in the slave cylinder. I removed mine and recognized an immediate improvement in clutch feedback/control; however you may have a faulty clutch master and/or slave cylinder.

[RElias21]

Originally Posted by Djdnav

I don't know if it's the cause of your issue, but there is a CDV. It's pre-installed in the slave cylinder. I removed mine and recognized an immediate improvement in clutch feedback/control; however you may have a faulty clutch master and/or slave cylinder.

Thank you for your response. How easy a job is this to do oneself? Did you replace the CDV with something else?

I would be surprised if I had a faulty part. Bought the car with 3k miles on it. Has 11k now and I don't beat on it.

[YKIGI]

Originally Posted by RElias21

Thank you for your response. How easy a job is this to do oneself? Did you replace the CDV with something else?

I would be surprised if I had a faulty part. Bought the car with 3k miles on it. Has 11k now and I don't beat on it.

Could be spark plug issue? You may get better response between gears by running colder plugs. Just a guess ?

[Ray Khan]

Here is how to remove it. I'll probably have mine done next spring. It doesn't look hard, but I don't want to deal with the mess or making sure the lines are properly pressurized afterwards.

https://f87.bimmerpost.com/forums/sh....php?t=1625114

[whitstap]

I removed the restrictor on the slave cylinder and the bite point on the clutch is definitely more consistent and easier to modulate as well slip off the line but I will say the car still loses some boost for a split second on upshifts... it seems like the more boost I run in midrange (target boost of tune) and the higher I rev before shifts (where the boost tapers below target) the longer it takes to recover on upshifts... so if I short shift before the boost tapers it holds much better to the point it gets seemless... this is with stock turbos fwiw not sure if it’s better on bigger turbos running boost levels within their efficiency range that can hold target all the way to redline

[RElias21]

Originally Posted by whitstap

I removed the restrictor on the slave cylinder and the bite point on the clutch is definitely more consistent and easier to modulate as well slip off the line but I will say the car still loses some boost for a split second on upshifts... it seems like the more boost I run in midrange (target boost of tune) and the higher I rev before shifts (where the boost tapers below target) the longer it takes to recover on upshifts... so if I short shift before the boost tapers it holds much better to the point it gets seemless... this is with stock turbos fwiw not sure if it’s better on bigger turbos running boost levels within their efficiency range that can hold target all the way to redline

Yes, this is exactly what I feel, and I also meant on upshifts.

I'm surprised this isn't more a topic of discussion on this forum and how to address.

[Djdnav]

Originally Posted by RElias21

Thank you for your response. How easy a job is this to do oneself? Did you replace the CDV with something else?

I would be surprised if I had a faulty part. Bought the car with 3k miles on it. Has 11k now and I don't beat on it.

Difficulty is subjective, however the slave cylinder is held on to the trans with 2 bolts, the hard line is held on with a clip, and there's a bracket with (1?) bolt that secures it. Since you disconnect the line, you need to bleed the slave a bit to let the air out. Also, the bolts are annoying to rethread into the trans, since it's at an odd angle.

The link posted a few replies above about covers it. I didn't replace the CDV with anything else, and experienced no leaks.

[Fat Goose]

Originally Posted by Djdnav

I don't know if it's the cause of your issue, but there is a CDV. It's pre-installed in the slave cylinder. I removed mine and recognized an immediate improvement in clutch feedback/control; however you may have a faulty clutch master and/or slave cylinder.

This. CDV delete takes about an hour. Did not like how this car drove before doing it, now its back to what I expected. Definitely recommend.

[edwinm3]

my 16' m4 which i bought new had no valve from factory

[Fat Goose]

Originally Posted by edwinm3

my 16' m4 which i bought new had no valve from factory

Yes it does.

[edwinm3]

Originally Posted by Rmnelson12

Yes it does.

nope, it did not , I've had multiple M cars throughout the years, some did have it and some didn't. For example my 08 E90 M3 had it and later my 10' E92 M3 didn't. Not sure why but I always check to remove it when flushing the brake fluid since I do track my cars.

[Fat Goose]

Originally Posted by edwinm3

nope, it did not , I've had multiple M cars throughout the years, some did have it and some didn't. For example my 08 E90 M3 had it and later my 10' E92 M3 didn't. Not sure why but I always check to remove it when flushing the brake fluid since I do track my cars.

Its because there is no physical "valve" like prior CDVs in prior models; it is literally a small, washer in the clutch slave cylinder. Trust me, its there.

[YRAGAEL]

To get rid of the CDV on my F80 I bought a slave cylinder from an E90. It's the exact same part but does not have the flow restrictor inside. I have yet to install it, but I can't wait to get it on there, as the clutch 'feel' on my car right now is basically non-existent. It's nearly impossible to get off the line smoothly, and I've tried enabling, and disabling rev matching in all drive modes. I got rid of the CDV on my previous E36 M3 and E90 335 - it always helps!

[Fat Goose]

https://f30.bimmerpost.com/forums/sh...1486773&page=5

I followed this method (post is in the middle of the pace), no drilling, just used a screw to pull out the “restrictor” CDV metal washer. Didn’t mess with any orings or have to remove anything. Best free mod for the 6MT!

[Djdnav]

Originally Posted by YRAGAEL

To get rid of the CDV on my F80 I bought a slave cylinder from an E90. It's the exact same part but does not have the flow restrictor inside. I have yet to install it, but I can't wait to get it on there, as the clutch 'feel' on my car right now is basically non-existent. It's nearly impossible to get off the line smoothly, and I've tried enabling, and disabling rev matching in all drive modes. I got rid of the CDV on my previous E36 M3 and E90 335 - it always helps!

There’s no reason to buy a new slave cylinder, just use a pick tool and pull the restrictor out of the one you have.

[MAddict]

I did the clutch delay valve removal myself last month, definitely recommend it. Big difference in clutch feel and smooth driving is much easier. I mentioned this mod to the senior shop foreman at dealer service dept, he said BMW has been using these delay valves since E36 days for hill assist in manuals. They even call it the hill assist valve between techs.

I recommend ordering a new slave for three reasons:
1) You have a backup in the original slave in case you mess anything up.
2) It's a wear item.
3) It's cheap.

The part # is 21-52-6-795-713 and runs about $90.

Also highly recommend using the Motive pressure bleeder to bleed the slave yourself, makes that much much easier.

Here's what you're after;

[jpy1980]

Sounds like a good mod!

Yet, this was installed by the factory for a reason. What are the negative consequences of doing this mod?

[Fat Goose]

“Helps” prevent shitty manual drivers from burning the clutch out. Training wheels

[Fat Goose]

Originally Posted by Djdnav

There’s no reason to buy a new slave cylinder, just use a pick tool and pull the restrictor out of the one you have.

Completely agree. Plus you don’t need take the slave cylinder off to do it.

[m3elmo]

I'm so happy to see this thread - I just got my F80 and was not understanding why the car feels like there is a slip of the clutch at the top. Or as the OP describes as a delay in power onset...i need to do this mod!

[Djdnav]

Originally Posted by m3elmo

I'm so happy to see this thread - I just got my F80 and was not understanding why the car feels like there is a slip of the clutch at the top. Or as the OP describes as a delay in power onset...i need to do this mod!

https://www.ebay.com/itm/F80-F82-E9X...0AAOxyrUtQ1H35

This also improved the feel of mine